Absorbent article including an absorbent core layer having a material free zone and a transfer layer arranged below the absorbent core layer

ABSTRACT

The present invention generally relates to absorbent articles and in particular to an absorbent article including a liquid permeable cover layer, a liquid impermeable barrier layer, an absorbent core arranged adjacent to the cover layer, a transfer layer arranged between the core and the barrier layer, the absorbent core including an upper surface and a lower surface and a material-free zone extending from the upper surface to the lower surface.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 12/554,047, filed Sep. 4, 2009, the entirety of whichapplication is hereby incorporated by reference herein as if fully setforth herein.

FIELD OF INVENTION

The present invention generally relates to absorbent sanitary napkinsand in particular to a sanitary napkin that has superior transverse andlongitudinal wicking characteristics, as well as superior fluidpenetration time and rewet properties.

BACKGROUND OF THE INVENTION

In order for a sanitary napkin to efficiently absorb a large amount offluid during use it must effectively wick fluid throughout the absorbentstructure of the napkin. Absent effective wicking properties menstrualfluid tends to pool in certain regions of the napkin as a result ofwhich the full absorbent capacity of the napkin is not effectivelyutilized. Accordingly, the inventors of the present invention haverecognized a need to provide a sanitary napkin that efficiently wicksfluid in the longitudinal and transverse directions of the napkin tothereby fully utilize the full absorbent capacity of the napkin, whilealso providing superior fluid penetration time and rewet properties.

SUMMARY OF THE INVENTION

In view of the foregoing, the present invention provides, according tofirst aspect of the invention, an absorbent article including alongitudinally extending centerline, a transversely extendingcenterline, a liquid permeable cover layer having a body facing surface,a liquid impermeable barrier layer, an absorbent core arranged adjacentto the cover layer, a transfer layer arranged between the absorbent coreand the barrier layer, the absorbent core including an upper surface anda lower surface and a material-free zone extending from the uppersurface to the lower surface, and the cover layer including a firstregion arranged in spaced relationship to the transfer layer and asecond region arranged in surface to surface contact with the transferlayer.

The present invention provides, according to second aspect of theinvention, an absorbent article including a longitudinally extendingcenterline, a transversely extending centerline, a liquid permeablecover layer having a body facing surface, a liquid impermeable barrierlayer, an absorbent core arranged adjacent to the cover layer, atransfer layer arranged between the absorbent core and the barrierlayer, the absorbent core including an upper surface and a lowersurface, the absorbent core including a plurality of beams and aplurality of material-free zones, each of the beams arranged in a spacedrelationship to an adjacent beam and each of the beams being separatedfrom an adjacent beam by a material-free zone, each of the material-freezones extending from the upper surface to the lower surface, the coverlayer including a plurality of first regions arranged in spacedrelationship to the transfer layer and a plurality of second regions,each of the second regions located between two adjacent beams andarranged in surface to surface contact with the transfer layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments of the present invention will now be describedwith reference to the drawings, in which:

FIG. 1 is a top perspective view of an absorbent article according tothe present invention;

FIG. 2 is a bottom perspective view of the absorbent article shown inFIG. 1;

FIG. 3 is an exploded view of the absorbent article shown in FIG. 1according to a first embodiment of the invention;

FIG. 4 is sectional view of the absorbent article shown in FIG. 1 takenalong line 4-4 in FIG. 1;

FIG. 5 is partially cut-away perspective view of the absorbent articleshown in FIG. 1 schematically depicting the path of fluid flow withinthe article;

FIG. 6 is an exploded view of the absorbent article shown in FIG. 1according to a second embodiment of the invention;

FIG. 7 is a sectional view of the absorbent article shown in FIG. 6taken along line 7-7 in FIG. 6;

FIG. 8 is a top perspective view of an absorbent article according to athird embodiment of the present invention;

FIG. 9 is an exploded view of the absorbent article shown in FIG. 8;

FIG. 10 is a sectional view taken of the absorbent article shown in FIG.8 taken along line 10-10 in FIG. 8;

FIG. 11 is a top elevation view of a test plate used to measure theLongitudinal Wicking Value (LWV), Transverse Wicking Value (TWV), andFluid Penetration Time (FPT) of an absorbent article; and

FIG. 12 is a schematic view depicting a stained absorbent articleaccording to the present invention and the manner in which theLongitudinal Wicking Value (LWV) and Transverse Wicking Value (TWV) aremeasured.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally relates to disposable absorbent articlessuch as sanitary napkins, pantiliners, absorbent products forincontinence, and other disposable absorbent articles worn close to awearer's body. Although the invention will be described herein withreference to a sanitary napkin, the invention may be utilized with otherdisposable sanitary absorbent articles such as absorbent products forincontinence, diapers, pantiliners and the like.

Absorbent articles according to the present invention provide superiorfluid handling characteristics, and more specifically provide superiorlongitudinal and transverse wicking characteristics, as well as superiorfluid penetration time and rewet properties.

As shown in FIGS. 1-4, the present invention relates to a sanitarynapkin 10 for absorbing bodily fluids. The sanitary napkin 10 includes abody facing surface 11, a garment facing surface 13, a longitudinallyextending centerline 15, and a transversely extending centerline 17.

As best seen in the exploded view shown in FIG. 3, the sanitary napkin10 includes a fluid permeable cover layer 12, an absorbent core 14, atransfer layer 16, and a fluid impermeable barrier layer 18. As shown inFIG. 3, the absorbent core 14 is arranged adjacent to the cover layer 12and the transfer layer 16 is arranged between the absorbent core 14 andthe barrier layer 18.

The absorbent core 14 includes a material-free zone 20 that is devoid ofany absorbent material. The material-free zone 20 extends from an uppersurface 19 of the absorbent core 14 to a lower surface 21 of theabsorbent core 14. The material-free zone 20 may be formed by any knownmethod such as cutting or the like. In the specific embodiment of theinvention shown in FIGS. 1-4 the material-free zone 20 is centrallyaligned with respect to the longitudinally extending centerline 15 andthe transversely extending centerline 17. In the specific embodiment ofthe invention shown in FIGS. 1-4, the material-free zone 20 issubstantially elliptical in shape and preferably has a length asmeasured along the longitudinally extending centerline 15 in the rangeof about 40 mm to about 160 mm and a width as measured along thetransversely extending centerline 17 of about 10 mm to about 60 mm. Thematerial-free zone 20 preferably extends over a surface area in therange of between 400 mm² and about 6000 mm².

As best seen in FIG. 4, the cover layer 12 includes a first region 22located outside the area of the material-free zone 20 that is arrangedin spaced relationship to the transfer layer 16 and the cover layerincludes a second region 24 within the area defined by the material-freezone 20 that is arranged in surface to surface contact with the transferlayer 16. The surface to surface contact of the cover layer 12 with thetransfer layer 16 essentially defines a gutter 29 in the body facingsurface 11 of the napkin 10. The absorbent core 14 preferably has athickness of between about 0.5 mm and about 20 mm. The depth of thegutter 29 is in the range of between about 0.5 mm and about 20 mm. Thethickness and depth measurements set forth in this paragraph may bedetermined by using a suitable thickness gauge such as the MitutoyoAbsolute Gauge or equivalent.

Reference is made to FIG. 5 which depicts the manner in which fluid isconveyed within the absorbent structure of a napkin 10 according to thepresent invention. As show, the transfer layer 16 directly receivesfluid from the cover layer 12 in the area of the material-free zone 20.The transfer layer 16 then wicks the fluid in the longitudinal andtransverse directions of the napkin until the fluid can be conveyedupward and absorbed into the absorbent core 14.

Reference is made to FIG. 6 which depicts an exploded view of a sanitarynapkin 10 a according to a second embodiment of the present invention.The sanitary napkin 10 a is similar in structure to the sanitary napkin10 described above but further includes a secondary absorbent core 26arranged between the primary absorbent core 14 and the transfer layer16. As shown, the secondary absorbent core 26 includes a material-freezone 28 that corresponds in size and shape to the material-free zone 20of the primary absorbent core 14. The material-free zone 28 extends froman upper surface 35 of the secondary absorbent core 26 to a lowersurface 37 of the secondary absorbent core 26.

Referring to FIG. 7, the cover layer 12 includes a first region 22located outside the area of the material-free zones 20 and 28 that isarranged in spaced relationship to the transfer layer 16 and the coverlayer includes a second region 24 within area of the material-free zones20 and 28 that is arranged in surface to surface contact with thetransfer layer 16. The surface to surface contact of the cover layer 12with the transfer layer 16 essentially defines a gutter 29 in the bodyfacing surface of the napkin 10. The primary absorbent core 14 and thesecondary absorbent core 28 preferably each has a thickness of betweenabout 0.5 mm and about 20 mm. The depth of each gutter 29 is in therange of between about 1.0 mm and about 40 mm.

Reference is made to FIGS. 8-10 which depict a sanitary napkin 10 baccording to a third embodiment of the present invention. As shown inFIG. 9, the sanitary napkin 10 b includes a includes a fluid permeablecover layer 12, an absorbent core 14, a transfer layer 16, and a fluidimpermeable barrier layer 18. As shown in FIG. 9, the absorbent core 14is arranged adjacent to the cover layer 12 and the transfer layer 16 isarranged between the absorbent core 14 and the barrier layer 18.

As best seen in the exploded view shown in FIG. 9, the absorbent core 14includes a plurality of longitudinally extending material-free zones 20that extend from an upper surface 19 of the absorbent core 14 to a lowersurface 21 of the absorbent core 14. Each of the material-free zones 20preferably has a width in the range of between 1 mm and about 10 mm anda length in the range of between about 50 mm and about 250 mm. Absorbentarticles according to the third embodiment of the present inventionpreferably have between about 2 and about 7 longitudinally extending thematerial-free zones 20. Each of the material free zones 20 is spacedfrom an adjacent material-free zone 20 in the transverse direction by adistance from about 5 mm to about 30 mm. Each material-free zones 20preferably extends over a surface area in the range of between about 50mm² and about 4000 mm². In the particular embodiment of the inventionshown in the FIGS. 8-10 the material-free zones 20 are linear in shape,parallel to each other, and equally spaced.

The absorbent core 14 further includes a plurality of longitudinallyextending beams 25, each of the beams 25 being arranged in spacedrelationship to an adjacent beam 25 and each of the beams 25 beingseparated from an adjacent beam 25 by one of the material-free zones 20.

As best seen in FIG. 10, the cover layer 12 includes a plurality offirst regions 22 that are arranged in spaced relationship to thetransfer layer 16 and a plurality of second regions 24 that are arrangedin surface to surface contact with the transfer layer 16. The surface tosurface contact of the cover layer 12 with transfer layer 16 in thesecond regions 24 essentially define a plurality of longitudinallyextending gutters 29 in the body facing surface 11 of the napkin 10 thatare coextensive with the path of the material-free zones 20. Theabsorbent core 14 preferably has a thickness of between about 0.5 mm andabout 20 mm. The depth of each gutter 29 is in the range of betweenabout 0.5 mm and about 20 mm.

Although not shown in the Figures, the sanitary napkin 10 b may beprovided with a secondary absorbent core arranged between the primarycore 14 and the transfer layer 16, the secondary absorbent coreincluding a plurality of material-free zones that correspond in shapeand size to the material-free zones of the primary core 14.

Although not shown in the Figures, the areas of the napkin in which thegutters 29 are located may be colored a different color than theremainder of the absorbent article. For example, the areas in which thegutters 29 are located may be colored blue while the remainder of thenapkin is generally white. By coloring the gutters 29 a different colorthan the remainder of the napkin, the enhanced wicking characteristicsprovided by the gutters 29 are visually communicated to a potential userof the absorbent article. The color may be imparted to the napkin byproviding a color (e.g., ink) to the cover layer 12 and/or the transferlayer 16 and/or the barrier layer 18.

Cover Layer

The cover layer 12 may be a relatively low density, bulky, high-loftnon-woven web material. The cover layer 12 may be composed of only onetype of fiber, such as polyester or polypropylene or it may include amixture of more than one fiber. The cover may be composed ofbi-component or conjugate fibers having a low melting point componentand a high melting point component. The fibers may be selected from avariety of natural and synthetic materials such as nylon, polyester,rayon (in combination with other fibers), cotton, acrylic fiber and thelike and combinations thereof. Preferably, the cover layer 12 has abasis weight in the range of about 10 gsm to about 75 gsm.

Bi-component fibers may be made up of a polyester layer and apolyethylene sheath. The use of appropriate bi-component materialsresults in a fusible non-woven fabric. Examples of such fusible fabricsare described in U.S. Pat. No. 4,555,430 issued Nov. 26, 1985 toChicopee. Using a fusible fabric increases the ease with which the coverlayer may be mounted to the absorbent layers of the article and/or tothe barrier layer.

The cover layer 12 preferably has a relatively high degree ofwettability, although the individual fibers comprising the cover may notbe particularly hydrophilic. The cover material should also contain agreat number of relatively large pores. This is because the cover layer12 is intended to take-up body fluid rapidly and transport it away fromthe body and the point of deposition. Therefore, the cover layercontributes little to the time taken for the napkin to absorb a givenquantity of liquid (penetration time).

Advantageously, the fibers which make up the cover layer 12 should notlose their physical properties when they are wetted, in other words theyshould not collapse or lose their resiliency when subjected to water orbody fluid. The cover layer 12 may be treated to allow fluid to passthrough it readily. The cover layer 12 also functions to transfer thefluid quickly to the underlying layers of the napkin. Thus, the coverlayer 12 is advantageously wettable, hydrophilic and porous. Whencomposed of synthetic hydrophobic fibers such as polyester orbi-component fibers, the cover layer 12 may be treated with a surfactantto impart the desired degree of wettability.

Alternatively, the cover layer 12 can be made of a polymer film havinglarge pores. Because of such high porosity, the film accomplishes thefunction of quickly transferring body fluid to the underlying absorbentlayers. A suitable cover material of this type is commercially found onthe STAYFREE Dry Max Ultrathin product distributed by McNeil-PPC, Inc.

The cover layer 12 may be attached to the underlying absorbent core 14,transfer layer 16, and/or the barrier layer 18, by adhesion and/or othersuitable means know to those of skill in the art.

Absorbent Core

In one embodiment, the absorbent core 14 is a blend or mixture ofcellulosic fibers and superabsorbent disposed therein. Cellulosic fibersthat can be used in the absorbent core 14 are well known in the art andinclude wood pulp, cotton, flax and peat moss. Wood pulp is preferred.Pulps can be obtained from mechanical or chemi-mechanical, sulfite,kraft, pulping reject materials, organic solvent pulps, etc. Bothsoftwood and hardwood species are useful. Softwood pulps are preferred.It is not necessary to treat cellulosic fibers with chemical debondingagents, cross-linking agents and the like for use in the presentmaterial. Some portion of the pulp may be chemically treated asdiscussed in U.S. Pat. No. 5,916,670 to improved flexibility of theproduct. Flexibility of the material may also be improved bymechanically working the material or tenderizing the material.

The absorbent core 14 can contain any superabsorbent polymer (SAP) whichare well known in the art. For the purposes of the present invention,the term “superabsorbent polymer” (or “SAP”) refers to materials whichare capable of absorbing and retaining at least about 10 times theirweight in body fluids under a 0.5 psi pressure. The superabsorbentpolymer particles of the invention may be inorganic or organiccrosslinked hydrophilic polymers, such as polyvinyl alcohols,polyethylene oxides, crosslinked starches, guar gum, xanthan gum, andthe like. The particles may be in the form of a powder, grains,granules, or fibers. Preferred superabsorbent polymer particles for usein the present invention are crosslinked polyacrylates, such as theproduct offered by Sumitomo Seika Chemicals Co., Ltd. Of Osaka, Japan,under the designation of SA70N and products offered by Stockhausen Inc.In a specific example, the absorbent core is a material containing from95% to about 40% percent cellulosic fiber by weight, and about 5% toabout 60% SAP by weight.

In one specific embodiment of the invention, the absorbent core 14 isconstructed from a mixture of fluff pulp, commercially available asRAYFLOC J-LD-E from Rayonier Products, Jessup, Ga., and superabsorbentpolymer commercially available under the designation SA70N from SumitomoSeika Chemicals Co., Ltd. Of Osaka, Japan, the mixture including 94%fluff pulp by weight and 6% superabsorbent polymer by weight.

Materials particularly suitable for use as the absorbent core preferablyhave a basis weight in the range from about 300 gsm (g/m²) to 1000 gsm,a thickness in the range of about 0.5 mm to 20 mm, and a density in therange of about 0.015 g/cc to 2 g/cc.

Transfer Layer

Adjacent to the barrier layer 18 layer on its inner side is the transferlayer 16. The transfer provides the means of receiving body fluid fromthe cover layer 12 and holding it until the absorbent core 14 has anopportunity to absorb the fluid, and therefore serves as a fluidtransfer or acquisition layer. In addition the transfer layer 16functions to wick the fluid in the longitudinal and transversedirections of the napkin so that the full absorbent capacity of thenapkin is utilized.

The transfer layer 16 is, preferably, has a larger proportion of smallerpores than the cover layer 12. These attributes allow the transfer layer16 to contain body fluid and hold it away from the outer side of thecover layer 12, thereby preventing the fluid from re-wetting the coverlayer 12 and its surface.

The transfer layer 16 may be composed of fibrous materials, such as woodpulp, polyester, rayon, flexible foam, or the like, or combinationsthereof. Preferably, the transfer layer 16 is free of any superabsorbentpolymer (SAP). The transfer layer 16 may also comprise thermoplasticfibers for the purpose of stabilizing the layer and maintaining itsstructural integrity. The transfer layer 16 may be treated withsurfactant on one or both sides in order to increase its wettability,although generally the transfer layer 16 is relatively hydrophilic andmay not require treatment. The transfer layer 16 is preferably bonded onboth sides to the adjacent layers, i.e. the absorbent core 14 and thebarrier layer 18.

Materials particularly suitable for use in the transfer layer 16 whichthe inventors have found contribute to reducing the penetration timehave a density in the range of about 0.04 to 0.05 g/cc, a basis weightin the range from about 80 to 110 g/m ² and a thickness in the range ofabout 1 to 3 mm. Examples of materials suitable for the first absorbentlayer are through air bonded pulp sold by BUCKEYE of Memphis, Tenn.under the designation VIZORB 3008, which has a basis weight of 110 g/m²and VIZORB 3010, which has a basis weight of 90 g/m ².

Barrier Layer

Underlying the transfer layer 16 is a barrier layer 18 comprisingliquid-impervious film material so as to prevent liquid from egressingthe sanitary napkin and staining the wearer's undergarment. The barrierlayer 18 is preferably made of polymeric film, although it may be madeof liquid impervious, air-permeable material such as repellent-treatednon-woven or micropore films or foams.

The barrier layer 18 may be breathable, i.e., permits vapor totranspire. Known materials for this purpose include nonwoven materialsand microporous films in which microporosity is created by, inter alia,stretching an oriented film. Single or multiple layers of permeablefilms, fabrics, melt-blown materials, and combinations thereof thatprovide a tortuous path, and/or whose surface characteristics provide aliquid surface repellent to the penetration of liquids may also be usedto provide a breathable backsheet. The cover layer 12 and the barrierlayer 18 are preferably joined along their marginal portions so as toform an enclosure or flange seal that maintains the transfer layer 16and absorbent core 14 captive. The joint may be made by means ofadhesives, heat-bonding, ultrasonic bonding, radio frequency sealing,mechanical crimping, and the like and combinations thereof.

Positioning adhesive may be applied to a garment facing surface 13 ofthe barrier layer 18 for securing the napkin 10 to a garment during use.As seen in FIG. 2, the positioning adhesive may be covered withremovable release paper 40 so that the positioning adhesive is coveredby the removable release paper 40 prior to use.

Absorbent articles of this invention may or may not include wings, flapsor tabs for securing the absorbent article to an undergarment. Wings,also called, among other things, flaps or tabs, and their use insanitary protection articles is described in U.S. Pat. No. 4,687,478 toVan Tilburg; U.S. Pat. No. 4,589,876 also to Van Tilburg, U.S. Pat. No.4,900,320 to McCoy, and U.S. Pat. No. 4,608,047 to Mattingly. Thedisclosures of these patents are incorporated herein by reference intheir entirety. As disclosed in the above documents, wings are generallyspeaking flexible and configured to be folded over the edges of theunderwear so that the wings are disposed between the edges of theunderwear.

Test Procedures

Absorbent articles according to the present invention possess acombination of unique functional properties. The test procedures setforth below highlight each of these functional properties. Prior toconducting any of the described test procedures described below the testproduct should be conditioned for two hours at 21 +/−1° C. and 50 +/−2%humidity.

Procedure for Longitudinal Wicking Value (LWV) and Transverse WickingValue (TWV)

Absorbent articles according to the present invention exhibit superiorwicking in the longitudinal and transverse directions of the article.The Longitudinal Wicking Value (LWV) and Transverse Wicking Value (TWV)test set forth below illustrates the superior wicking characteristics ofabsorbent articles according to the present invention.

Absorbent articles according to the present invention have preferablyhave LWV greater than 60, more preferably greater than 70, and mostpreferably greater than 75.Absorbent articles according to the presentinvention preferably have a TWV greater than 35, more preferably greaterthan 40, and most preferably greater than 45.

The synthetic test fluid described below is used in the test methoddescribed below. The synthetic test fluid used in replacement of humanmenses due to its ease in preparation and accessibility of theingredients.

The fluid is prepared by dissolving each of the following componentsinto distilled water. Care should be taken to ensure that components arewell dissolved. A rotating blade mixer or a magnetic stirrer should beused for mixing the components. In a large enough container, add thefollowing components, making sure that the component is dissolved beforeadding the next one:

Catalog Quantity/1 L Reagent Grade, purity Supplier No. 9.0 g sodiumchloride ACS reagent Sigma-Aldrich 223514 99+% 490.5 g distilled waterN/AP N/AP N/AP 10 g 2-phenoxyethanol puriss. 99.0% Sigma-Aldrich  77699(Fluka) 0.5 g FD&C Red #40 Food A&C C3465 490.5 g Glycerol ACS reagentSigma-Aldrich G7893 99.5%

The materials required to determine the LWV and TWV include thefollowing:

-   -   a poly(methylmetracrylate) (Plexiglas) template 200, shown in        FIG. 11, having dimensions of 200 mm long×60 mm wide×12.7 mm        thick and an elliptical orifice 202 (30.8 mm×19 mm) in the        center of the template;    -   a calibrated electronic repeater pipette (HandyStep Electronic        Repeating Pipet, Brandtech) with a 50 mL combi-syringe (or        combi-tip) capable of delivering 5-10 mL at a rate of        approximately 4 mL/s and fixed on a stand with the end of the        tip placed vertically at 25.4 mm (1 inch) from the surface of        the product;    -   a calibrated stopwatch that has a precision of 0.01 s;    -   a ruler graduated in millimeters (mm);    -   a fine point permanent marker; and    -   the test fluid prepared according to the procedure described        above.

To obtain the LWV and TWV, the conditioned article is removed from itspackaging, unfolded, placed on a flat surface (e.g. lab table). ThePlexiglas plate 200 is placed and centered over the absorbent product,light hand applied pressure is applied to flatten the article, withoutcompressing it, such that there is no substantial bending or folding ofthe article under the template 200.

A 50 mL combi-syringe (or combi-tip), placed on a repeater pipette, isfilled with the test fluid, positioned vertically and fixed on a standwith the end of the tip placed approximately 1 inch from the surface ofthe product and above the center of the elliptical hole 202 of theplate. The article should be arranged such that the intersection of thelongitudinally extending and transversely extending centerlines ispositioned in the center of the hole 202. Then, 10 mL of test fluid isinsulted to the article at a rate of approximately 4 mL/s. The stopwatchis started as soon as the repeating pipet button is pressed to dispensethe volume. After 60 s, the plate is removed and the limits of thestain, along the longitudinally extending and transversely extendingaxes, are marked rapidly (within less than 10 s) with a marker. Only thecontinuous fluid stain limits found on the article cover are marked,fluid spots not continuous or linked to the rest of the fluid flowand/or observed in the lower layers of the absorbent product are notconsidered in the determination of the wicking distance. Using thefurthest continuous points found along the longitudinally andtransversely extending axes, a rectangle is drawn as shown in FIG. 12.The length of the rectangle measured in the longitudinal direction isthe LWV and the length of the rectangle in the transverse direction isthe TWV.

Thus the Longitudinal Wicking Value is the farthest continuous fluiddisplacement along the longitudinally extending centerline 15 of thearticle, and the Transverse Wicking Value is the farthest continuousfluid displacement along the transversely extending centerline 17. Alldistance values are measured with a ruler to a precision of 1 mm.

If the test fluid touches or runs over the edges of the plate 200 in thetransverse direction within 60 s following the fluid injection, thesample is considered to have failed and a zero (0) TWV is attributed tothat sample. If the absorbent article being tested is smaller than thetest plate 200, then failure is defined as the moment when the fluidreaches the edges of the absorbent article in the transverse direction.

This procedure is repeated five times using three different samples ofeach type of absorbent article and an average LWV and TWV is calculatedfrom these three repeats. If any of the five products fails, i.e. thefluid reaches the edges of the plate, then the reported average TWV iszero (0).

Procedure for Measuring Fluid Penetration Time (FPT)

Absorbent articles according to the present invention preferably have afluid penetration time of less than 10 s, more preferably less than 8 s,and most preferably less than 5 s.

Fluid Penetration Time is measured by placing a sample to be testedunder the template 200, shown in FIG. 11. The template 200 is arrangedon the product sample so that the center of the elliptical orifice isaligned with the intersection of longitudinally extending centerline 15and transversely extending centerline 17 of the product. Thelongitudinal axis of the elliptical orifice is aligned to thelongitudinal axis of the product to be tested. Test fluid having theformula set forth above is utilized as the test fluid for the fluidpenetration time procedure.

A graduated 10 ml syringe containing 7 ml of test fluid is held over theorifice plate such that the exit of the syringe is approximately 3inches above the orifice. The syringe is held horizontally, parallel tothe surface of the test plate. The fluid is then expelled from thesyringe at a rate that allows the fluid to flow in a stream vertical tothe test plate into the orifice and a stopwatch is started when thefluid first touches the sample to be tested. The stopwatch is stoppedwhen a portion of the surface of the sample first becomes visible abovethe remaining fluid within the orifice. The elapsed time on thestopwatch is the Fluid Penetration Time. The average Fluid PenetrationTime (FPT) is calculated from taking the average of three productsamples.

Procedure for Measuring Rewet Potential

Absorbent articles according to the present invention preferably have aRewet Potential of less than 1.0 g and more preferably less than 0.6 g.

The three product samples used for the Fluid Penetration Time (FPT)procedure described above are used for the Rewet Potential testdescribed below.

The rewet potential is a measure of the ability of a napkin or otherarticle to hold liquid within its structure when the napkin contains arelatively large quantity of liquid and is subjected to externalmechanical pressure. The rewet potential is determined and defined bythe following procedure.

The apparatus for the Rewet Potential test is the same as that set forthabove with regard to the Fluid Penetration Time test and furtherincludes a quantity of 3 inch×4 inch rectangles of Whatman #1 filterpaper (Whatman Inc., Clifton, N.J.) and a weighing machine or balancecapable of weighing to an accuracy of +/−0.001 g, a quantity of saidWhatman paper, a standard weight of 2.22 kg (4.8 pounds) havingdimensions 51 mm (2 inches) by 102 mm (4.0 inches) by approximately 54mm (2.13 inches) which applies a pressure of 4.14 kPa (0.6 psi) over the51 mm by 102 mm (2 inches by 4 inches) surface.

For purposes of the test procedure set forth herein, the same threeproduct samples used for the fluid penetration test should be used forthe rewet potential test. After the test fluid is applied within theorifice plate in the Fluid Penetration Time test described above, and assoon as the cover layer of the napkin first appears through the topsurface of the fluid, the stopwatch is started and an interval of 5minutes is measured.

After 5 minutes have elapsed, the orifice plate is removed and thenapkin is positioned on a hard level surface with the cover layer facingupwards.

A fifteen (15) layer stack of the pre-weighed filter paper is placed onand centered over the wetted area and the standard 2.22 kg weight isplaced on top of the filter paper. The filter paper and the weight arearranged over the absorbent article such that they are centered over thearea to which the fluid was applied. The filter paper and the weight arearranged such that their longer dimensions are aligned with thelongitudinal direction of the product. Immediately after placing thepaper and weight on the product, the stopwatch is started and after a 3minute interval has elapsed the standard weight and filter paper arequickly removed. The wet weight of the filter paper is measured andrecorded to the nearest 0.001 grams. The rewet value is then calculatedas the difference in grams between the weight of the wet 15 layers offilter paper and the dry 15 layers of filter paper.

The measurement should have at least three replicates and, if necessary,the weight is wiped clean before each run. The average rewet value (R)is then calculated from the three measured values.

EXAMPLES Inventive Example

An inventive example of a sanitary napkin according to the presentinvention was constructed as follows.

The cover layer was a thermo bonded nonwoven cover having a basis weightof 16 gsm (polypropylene fibers) commercially available from Polystarunder product code 142250. The core facing surface of the cover wastreated with a construction adhesive commercially available fromBostik-Findley under product code H-2900. The adhesive was applied in anamount of 5.0 gsm over a 95 mm×230 mm portion of the cover. The treatedside of the cover was placed on top of an absorbent core. The absorbentcore was constructed with a material free zone of the type shown in FIG.1 having a width of 30 mm as measured along the transversely extendingcenterline of the article and length of 100 mm as measured along thelongitudinally extending centerline of the article. The material freezone extended over a surface area of 2305.91 mm². The core had athickness of 5.5 mm. The gutter defined by the material free zone had adepth of 4.4 mm. The absorbent core was constructed from 5.0 g of woodpulp commercially available from Georgia Pacific under product code111410 and 0.4 g super absorbent polymer commercially available fromSumitomo Seika Ltd. under product code SA70. The core had a density of0.103 g/cc. The transfer layer was constructed from a 75 gsm airlaidcommercially available from Buckeye of Memphis, Tenn. under product codeX853-2. The transfer layer was placed on a polyethylene film barrierlayer commercially available from Clopay under product code 113689. Thetransfer layer had a density of 0.058 g/cc. The transfer layer wasattached to the core by applying adhesive, code H-2900 fromBostik-Findley, in an amount of 5.0 gsm over an area of 40 mm (width) by100 mm (length). The transfer layer was attached to the barrier byapplying adhesive, H-2900 from Bostik-Findley, in an amount of 3.6 gsmover the surface of the barrier layer.

Comparative Example #1

Comparative Example #1 was constructed from the same materials asdescribed in the Inventive Example however the transfer layer wasarranged between the cover layer and the core and the core wasconstructed as a solid layer, i.e. the core did not contain any materialfree zone.

Comparative Example #2

Comparative Example #2 was an Always Regular Maxi (lot #82434786421709UPC3700030563).

Each of the Inventive Example, Comparative Example #1 and ComparativeExample #2 were tested according to the test methods described above andthe results thereof are summarized in Table 1 provided below.

TABLE 1 Compa- Inventive Comparative rative (average of n = 3) ExampleExample #1 Example #2 Transverse Wicking Value (TWV) 49.6 32.2 30.4Longitudinal Wicking Value (LWV) 79 50.6 50.4 Fluid Penetration Time(FPT) 4.3 11.9 2.9 Rewet Value 0.49 0.05 2.7

As illustrated in the table provided above absorbent articles accordingto the present invention provide superior fluid handling characteristicswhen compared to comparable prior art articles.

I claim:
 1. An absorbent article comprising: a longitudinally extendingcenterline; a transversely extending centerline; a liquid permeablecover layer having a body facing surface; a liquid impermeable barrierlayer; an absorbent core arranged adjacent to the cover layer; atransfer layer arranged between the core and the barrier layer; whereinthe absorbent core includes an upper surface and a lower surface and amaterial-free zone extending from the upper surface to the lowersurface; and wherein the cover layer includes a first region arranged inspaced relationship to the transfer layer and a second region arrangedin surface to surface contact with the transfer layer.
 2. The absorbentarticle according to claim 1, wherein the material-free zone iscentrally aligned with respect to the longitudinally extendingcenterline and the transversely extending centerline.
 3. The absorbentarticle according to claim 2, wherein the material-free zone extendsover an area between about 400 mm² and about 6000 mm².
 4. The absorbentarticle according to claim 3, wherein the material-free zone issubstantially elliptical in shape and preferably has a length asmeasured along the longitudinally extending centerline in the range ofabout 40 mm to about 250 mm and a width as measured along thetransversely extending centerline of about 10 mm to about 60 mm.
 5. Theabsorbent article according to claim 4, wherein the transfer layer,absorbent core and cover cooperate to define a longitudinally extendinggutter in the body facing surface of the article, the gutter having adepth in the range of between about 0.5 mm and about 20 mm.
 6. Theabsorbent article according to claim 1, wherein the absorbent articlehas a LWV greater than
 60. 7. The absorbent article according to claim6, wherein the absorbent article has a TWV greater than
 35. 8. Theabsorbent article according to claim 7, wherein the absorbent articlehas a FPT less than 10 seconds.
 9. The absorbent article according toclaim 8, wherein the absorbent article has Rewet Value less than 1 g.10. The absorbent article according to claim 1, wherein the transferlayer is free of superabsorbent material.
 11. The absorbent articleaccording to claim 10, wherein the absorbent core comprises a mixture ofcellulosic fiber and superabsorbent polymer, the absorbent corecontaining from 95% to about 40% percent cellulosic fiber by weight, andabout 5% to about 60% superabsorbent polymer by weight.
 12. Theabsorbent article according to claim 1, further comprising a secondaryabsorbent core arranged between the absorbent core and the transferlayer, wherein the secondary absorbent core includes a material-freezone extending from an upper surface of the secondary absorbent core toa lower surface of the secondary absorbent core, and wherein thematerial-free zone of the secondary absorbent core corresponds in sizeand shape to the material-free zone of the core.
 13. The absorbentarticle according to claim 12, wherein the transfer layer, absorbentcore, secondary absorbent core, and cover cooperate to define alongitudinally extending gutter in the body facing surface of thearticle, the gutter having a depth in the range of between about 1.0 mmand about 40 mm.
 14. An absorbent article comprising: a longitudinallyextending centerline; a transversely extending centerline; a liquidpermeable cover layer having a body facing surface; a liquid impermeablebarrier layer; an absorbent core arranged adjacent to the cover layer; atransfer layer arranged between the core and the barrier layer; whereinthe absorbent core includes an upper surface and a lower surface, theabsorbent core comprising a plurality of beams and a plurality ofmaterial-free zones, each of the beams arranged in a spaced relationshipto an adjacent beam and each of the beams being separated from anadjacent beam by a material-free zone, each of the material-free zonesextending from the upper surface to the lower surface; and wherein thecover layer includes a plurality of first regions arranged in spacedrelationship to the transfer layer and a plurality of second regions,each of the second regions located between two adjacent beams andarranged in surface to surface contact with the transfer layer.
 15. Theabsorbent article according to claim 14, wherein each of thematerial-free zones preferably has a width in the range of between about1 mm and about 10 mm and a length in the range of between about 40 mmand about 250 mm.
 16. The absorbent article according to claim 15,wherein the absorbent article includes between 2 and about 7longitudinally extending the material-free zones and each of thematerial free zones is spaced from an adjacent material-free zone in thetransverse direction by a distance from about 5 mm to about 30 mm. 17.The absorbent article according to claim 16, wherein each of thematerial-free zones extend over a surface area in the range of between50 mm² and about 4000 mm².
 18. The absorbent article according to claim16, wherein the transfer layer, absorbent core and cover cooperate todefine a plurality of longitudinally extending gutters in the bodyfacing surface of the article, each of the gutters having a depth in therange of between about 0.5 mm and about 20 mm.
 19. The absorbent articleaccording to claim 18, wherein the absorbent article has a LWV greaterthan
 60. 20. The absorbent article according to claim 19, wherein theabsorbent article has a TWV greater than
 40. 21. The absorbent articleaccording to claim 20, wherein the absorbent article has a FPT less than5 seconds.
 22. The absorbent article according to claim 21, wherein theabsorbent article has Rewet Value less than 1 g.
 23. The absorbentarticle according to claim 14, wherein the transfer layer is free ofsuperabsorbent material.
 24. The absorbent article according to claim23, wherein the absorbent core comprises a mixture of cellulosic fiberand superabsorbent polymer, the absorbent core containing from about 95%to about 40% percent cellulosic fiber by weight, and about 5% to about60% superabsorbent polymer by weight.